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Equipment buying guides

Monochrome cameras — control over the bands

A sensor without a colour mosaic records the intensity reaching it. Colour images usually require separate exposures through different filters.

It offers flexible LRGB and narrowband work, but the full system costs more and needs filter sequencing, focus and calibration planning.

Objective lens · Sensor and image field12
  1. 1Objective lens
  2. 2Sensor and image field
Functional schematic, not to scale. Rays and component shapes are simplified; this is not a particular model’s optical prescription.

What is it good for?

Recording images unlike the direct eyepiece view, plus measuring and processing signals across frames.

Limitations and trade-offs

Large sensors need an adequate image circle and filters. Cooling cannot replace integration time, focus or tracking.

Check before buying

  • Sensor field and pixel scale
  • Read noise, cooling and recording modes
  • Drivers, power and backfocus

Compare the whole optical train, not just the sensor model in a specification list.

Matching your setup

First check that the target fits and the optics illuminate the sensor adequately. For small angles, field width in degrees is approximately 57.3 × sensor width / focal length, using the same length units.

Image scale in arcseconds per pixel is about 206.265 × pixel size in µm / focal length in mm. For example, 3.76 µm at 500 mm gives about 1.55″/pixel. Finer sampling cannot arbitrarily overcome atmosphere and optical resolution.

Check raw-data recording and calibration. Stable temperature makes repeatable darks easier, but appropriate flats and optical-train checks still matter. Allow for storage requirements and computer performance too.

Documentation and further reading
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